The following U.S. Pat. Nos. exemplify the state of the art of selectively self-sealing drain valves: 4,103,372, 3,771,177, 3,428,295, 3,380,081, 3,366,980, 2,173,529.
It is well known in the art to provide sealable drain fittings, particularly in domestic use for bathtubs, sinks, and the like. These drains are generally provided with a remote actuator which is linked to the drain itself by a lever or chain arrangement. Over a period of years, these drains and the lever or chain linkages undergo erosion and wear, and eventually fail. Due to the fact that the linkage is usually located within a wall or beneath a bathtub or sink, it is usually quite difficult to gain access to the linkage for the purpose of making repairs. Because of the expense and trouble involved in such repairs, a homeowner often avoids such costs by providing a replacement sealable drain valve which does not require a remote actuator.
Generally speaking, these replacement drain valves may be installed in the body of the original drain valve, and often include a drain cover which translates axially to seal the top opening of the replacement valve. The prior art devices are resiliently biased to the upwardly extending, open position by means of resilient rubber sleeves or by helical compression springs. The devices generally include a latch detent mechanism which secures the drain cover in a closed position in opposition to the resilient force applied thereto. In these devices, to release the drain cover it is necessary to press a small edge portion thereof to disengage the latch. For the uninitiated and uninformed, it is an inconvenience to attempt to determine which portion of the cover must be pressed to open the drain valve. This situation may be exacerbated when the drain cover is obscured from view by the water which is retained thereby.